The Brain as Tape Recorder

Hippocrates revolutionized medical thinking when he moved the seat of reason from the heart to the head and wrote: "From the brain, and from the brain only, arise our pleasures, joys, laughter and jests, as well as our sorrows, pains, griefs and tears." Since then (circa 400 B.C.), says famed Neurosurgeon Wilder Penfield, a few highly localized parts of the brain have been shown to control vision, hearing, speech, some physical sensations and most movements, but by far the greater part of the brain remains unexplored. To fill in one of the blanks on the cerebral map, Dr. Penfield has just offered evidence to the National Academy of Sciences that parts of the brain work like an audio-video tape recorder, preserving the details of everything a man sees and hears.

Before operating on epilepsy patients, Dr. Penfield, head of Montreal's Neurological Institute, explores the surface of their brains with a fine electrode (usual current: 1-5 volts for 1/500 to 1/200 second). Though fully conscious (only local anesthesia is used for opening the skull), the patient feels no shock, does not even know when the current is applied, for the brain tissue itself is insensitive to pain.

Built-in Hi-Fi. Examining a woman patient this way in 1931, Dr. Penfield touched part of the left temporal lobe. She began to recall giving birth more than 20 years earlier. When the electrode was applied to the cut surface in the forward part of the temporal lobe during an operation on a 26-year-old secretary, she suddenly remarked: "I hear music." Minutes later, without her knowledge, the electrode was reapplied to the same spot. "I hear music again," she said. She hummed the tune in time with the orchestra that she heard. Later she wrote: "It is not one of my favorite songs, so I don't know why I heard that one. I finally got hold of a copy and played it on the piano."

Other patients also had musical recollections. One heard a piano and saw the man playing it. A boy reported seeing men seated in chairs and hearing them sing. These were no hallucinations, but always the reproductions of actual experiences. Aside from music, patients have recalled a wide variety of incidents, usually trivial, often from childhood, and connected with the family or neighbors.

More Real Than Memory. Dr. Pen-field's conclusion: "There is, hidden away in the brain, a record of the stream of consciousness. It seems to hold the detail of that stream as laid down during each man's waking, conscious hours. Contained in this record are all those things of which the individual was once aware--such details as a man might hope to remember for a few seconds or minutes afterwards, but which are largely lost to voluntary recall after that time . . .

"This is not memory, as we usually use the word. No man can recall by voluntary effort such a wealth of detail . . . Many a patient has told me that the experience brought back by the electrode is much more real than remembering."

Strangely, two experiences--or "strips of time," as Dr. Penfield calls them--are never activated at the same time, so there is no confusion. Responses are obtained only from the lobes lying inside the temples, never from the frontal lobes (in the forehead) or the occipital (toward the back of the head). Even in some parts of the temporal lobes themselves, stimulation produces no effect. And never does stimulation lead to constructive thinking or purposeful action.

Interpretive Cortex. Dr. Penfield is confident that the temporal lobe areas he has studied are only transmission belts for the electrical impulses that pass through the brain at the time of the original experiences, and that the actual storehouse of the impressions is in a deeper part of the brain. His electric needling sends an impulse to this storehouse that revives the experience. But it does something more: he finds that often, when his patients are stimulated, they have a "feeling about the present situation--an interpretation of the present, but not one that the patient thinks out deliberately."

So, Dr. Penfield reasons, his stimulations of the temporal lobe are like a process that is common in everyday life: a flashback of past experience, and an almost instantaneous comparison of the present with previous similar experiences. For this area of the brain, to which no function had been assigned, he proposes the term "interpretive cortex." Its discovery, he suggests, is a step toward explaining what Hippocrates called the brain's power to "distinguish the ugly from the beautiful, the bad from the good, the pleasant from the unpleasant."

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